Tumors cannot grow without blood vessels that supply cancer cells with oxygen and nutrients (Blagosklonny, International J. Oncol., 2001 19: 257–262). Control of the hypoxic response in mammalian cells by the transcription factor, HIF-1 is one of the major regulators of cancer cell growth. HIF renders cells capable of surviving hypoxia and stimulating endothelial growth and it is upregulated in a broad range of cancers (Zhong et al., Cancer Res. 1999 59: 5830–5835). One of the most striking examples of the role of HIF in angiogenesis and tumor progression is the loss of function of the protein, VHL, which is a tumor suppressor gene that is mutated in most sporadic clear-cell renal carcinoma and in VHL disease. Therefore disruption of the HIF-1 pathway inhibits tumor growth, indicating HIF-1 as a potential anticancer target. Inhibition of HIF-1 is a mechanism-based anti-angiogenic strategy because it is the HIF-mediated response that drives tumor angiogenesis. U.S. Pat. No. 6,222,018 issued to Semenza, Apr. 24, 2001, relates to the nucleotide sequences encoding HIF-1. The specific oligonucleotides disclosed and claimed in the present invention were not disclosed in that patent.